Materials for preparing a color filter for a liquid crystal display are usually colored negative photoresist. A color filter is prepared in a process of coating the colored negative resists onto the surface of a glass substrate, followed by pre-bake, exposure, imaging and after-bake.
In order to achieve higher resolution and more colorful effect, the colored photoresist has to have a compact and level surface. However, during the preparation, surface defects such as orange peel, shrinkage, Bernard cells, etc., may occur on the surface due to multiple reasons, which cause the film not level and severely affect the display performance. The common treatment method against the above is the addition of a leveling agent.
In the meanwhile, to increase the imaging efficiency of the color filter, a higher amount of high viscosity alkaline soluble resin is often added into the formulation of its raw material, the colored photoresist. However, this renders the viscosity of the system too high, and limits the ability of the photoresist to self-level. If the content of the alkaline soluble resin is decreased, although the viscosity of the system can be reduced so as to improve the leveling, the adverse effect caused by remnants may occur.
To solve the above problem, it is required to improve the flexibility and the alkaline resistant (that is, crosslinking capacity) after the exposure of the chain segments of the alkaline soluble resin.